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排序方式: 共有350条查询结果,搜索用时 31 毫秒
101.
Cheng-Lin Liu Author Vitae Kazuki Nakashima Author VitaeAuthor Vitae Hiromichi Fujisawa Author Vitae 《Pattern recognition》2004,37(2):265-279
The performance evaluation of various techniques is important to select the correct options in developing character recognition systems. In our previous works, we have proposed aspect ratio adaptive normalization (ARAN) and have evaluated the performance of state-of-the-art feature extraction and classification techniques. For this time, we will propose some improved normalization functions and direction feature extraction strategies and will compare their performance with existing techniques. We compare ten normalization functions (seven based on dimensions and three based on moments) and eight feature vectors on three distinct data sources. The normalization functions and feature vectors are combined to produce eighty classification accuracies to each dataset. The comparison of normalization functions shows that moment-based functions outperform the dimension-based ones and the aspect ratio mapping is influential. The comparison of feature vectors shows that the improved feature extraction strategies outperform their baseline counterparts. The gradient feature from gray-scale image mostly yields the best performance and the improved NCFE (normalization-cooperated feature extraction) features also perform well. The combined effects of normalization, feature extraction, and classification have yielded very high accuracies on well-known datasets. 相似文献
102.
Takahiro Murakami Hiromichi Kobayashi Yoshihiro Okuno Shigeharu Kabashima 《Electrical Engineering in Japan》1999,126(4):48-54
The influence of azimuthal non‐uniformity of the seed fraction on plasma structure and performance in a non‐equilibrium disk MHD generator is investigated with a two dimensional r–θ numerical simulation. It is found that a locally high seed fraction causes mainly non‐uniformity of gas‐dynamical properties, whereas a locally low seed fraction develops a non‐uniform plasma. Both locally high and low seed fractions reduce generator performance considerably. These results suggest a spatially uniform seed fraction should be required for high power generation. ©1999 Scripta Technica, Electr Eng Jpn, 126(4): 48–54, 1999 相似文献
103.
Structural and chemical stabilities of substituted hexaaluminate catalyst films coated on some ceramic substrates were investigated for high-temperature combustion applications. The thermal stability of the hexaaluminate catalyst films on -SiC substrate was greatly enhanced by the insertion of both, a neat hexaaluminate and mullite intermediate layer. Pure alumina substrate was preferable in depositing the substituted hexaaluminate catalyst film to pure mullite, mullite-zirconia composite, or partially stabilized zirconia substrates. The thermal stability of the hexaaluminate catalyst films, coated on these oxide ceramic substrates, greatly depended on the extent of diffusion of components between the film and substrate at high temperatures. The substituted hexaaluminate microparticles in the film rearranged during the sintering process above 1400°C, and their (00l) plane oriented parallel to the surface of the substrate. Manganese introduced in the substituted hexaaluminate films or disks gradually decreased with an increase in the heat-treatment temperature because of its volatilization. 相似文献
104.
Enrico Traversa Stefano Villanti Gualtiero Gusmano Hiromichi Aono Yoshihiko Sadaoka 《Journal of the American Ceramic Society》1999,82(9):2442-2450
Ultrafine SmFeO3 powders were prepared by the thermal decomposition at 700°C of the corresponding hexacyanocomplex, Sm[Fe(CN)6 ]·4H2 O. These powders were used for the preparation of pastes which were deposited as thick films on alumina substrates with comb-type Au electrodes. The films were fired at different temperatures in the 800-1000°C range. The content of α-terpineol, a component of the organic vehicle, was varied in the range 0.0046-4 wt%. The microstructure, the chemical composition at the surface, the electrical conductivity, and the NO2 sensing properties of the films were investigated. The content of α-terpineol strongly influenced the electrical conductivity and its activation energy. A significant reduction in the NO2 response was observed for the films containing smaller amounts of α-terpineol, together with an increase in conductivity. On the other hand, the largest NO2 response was observed for the films fired at 1000°C when 4 wt% of α-terpineol was used. Such increase in conductivity is attributed to a different oxygen surface layer on the SmFeO3 surface, which is induced by the decomposition reaction of α-terpineol during sintering. The materials processing parameters are thus of primary concern for the NO2 sensing properties of the SmFeO3 thick films. The correlations found between activation energy, NO2 sensitivity, and materials characteristics (influenced by the preparation parameters) are reported. These correlations can be used to design the gas-sensing properties of SmFeO3 thick films for the optimization of their sensing characteristics. 相似文献
105.
Yifan Zhang Kecheng Cao Takeshi Saito Hiromichi Kataura Hans Kuzmany Thomas Pichler Ute Kaiser Guowei Yang Lei Shi 《Nano Research》2022,(3):1709-1714
Sub-nanometer armchair graphene nanoribbons(GNRs)with moderate band gap have great potential towards novel nanodevices.GNRs can be synthesized in the confined t... 相似文献
106.
ABSTRACT The isotopic exchange rate of Cs+ between hydrous niobium(V) oxide in the Cs+ form and aqueous solutions was determined radiochemically. The rate was controlled by the diffusion of Cs+ in the exchanger particle at varying pH. The diffusion coefficients at 10°C increased with pH up to pH7; from 3.0x10?11 m2s?1 at pH6 to 4.0×10?11 m2s?1 at pH7, and became constant above pH8 (5.0x10?11 m2s?1). While the diffusion coefficients of Na+ monotonously decrease with increasing pH; from 7.9×l0?11 m2s?1 at pH6.5 to 2.8×l0?11 m2s?1 at pHll. The difference in the dependence of diffusion coefficients on pH between Cs+ and Na+ was interpreted in terms of strength of interaction between counterions and ion-exchange sites since hydrous niobium(V) oxide has selectivity higher for Cs+ than for Na+. 相似文献
107.
Hiromichi Aono Takaaki Nishida Masato Kurihara Masatomi Sakamoto Yoshihiko Sadaoka 《Ceramics International》2012,38(3):2333-2338
New heteronuclear (NH4)REIII[FeII(CN)6]·nH2O complexes (RE = La, Ce, Pr, Nd, Sm, Gd, Dy, Y, Er, Lu) were synthesized and their thermal decomposition products were investigated. The crystal structure of (NH4)RE[FeII(CN)6]·nH2O would be a hexagonal unit cell (space group: P63/m), which was the same as that of La[FeIII(CN)6]·5H2O. The hydration number n = 4 was estimated by TG results for all the RE complexes. The lattice constants depended on the ionic radius of the RE3+ ion for the heteronuclear complexes. The single phase of the perovskite type materials was directly obtained by decomposition of the heteronuclear complexes for RE = La, Pr, Nd, Sm, and Gd. A mixture of CeO2 and Fe2O3 was formed for RE = Ce because of its oxidation to Ce4+. In the case of RE = Dy, Y, Er, and Lu complexes, the perovskite type materials formed at higher temperature via. mixed oxides such as RE2O3 and RE4Fe5O13 due to the small RE3+ ionic radius. 相似文献
108.
Yi Feng Wang Kyu Hyoung Lee Hiromichi Ohta Kunihito Koumoto 《Ceramics International》2008,34(4):849-852
To clarify the effect of substitutional electron doping on the thermoelectric figure of merit (ZT = S2σTκ−1) of Ruddlesden–Popper phase SrO(SrTiO3)n (or Srn+1TinO3n+1), measurements were conducted for several thermoelectric parameters, e.g. electrical conductivity (σ), Seebeck coefficient (S) and thermal conductivity (κ), of (Sr1−xREx)n+1TinO3n+1 (n = 1 or 2, RE (rare earth): La or Nd, x = 0.05 and 0.1) dense ceramics prepared by a conventional solid-state reaction and hot-pressing technique. Crystal structures of the resultant ceramics were represented as (Sr1−xREx)n+1 TinO3n+1 evaluated by powder X-ray diffraction followed by the Rietveld analysis. All the ceramics exhibited electrical conductivity and the σ values simply depended on the dopant concentration, indicating that both La3+ and Nd3+ ions act as electron donors. The |S| values increased with temperature due to decrease in the chemical potential. Significant reduction of the κ values was observed as compared to cubic-perovskite SrTiO3. The ZT value increased with temperature and reached 0.15 at 1000 K for (Sr0.95La0.05)3Ti2O7. 相似文献
109.
Kyu Hyoung Lee Yi Feng Wang Sung Wng Kim Hiromichi Ohta Kunihito Koumoto 《International Journal of Applied Ceramic Technology》2007,4(4):326-331
We report herein on Ruddlesden–Popper-type doped Sr n +1 Ti n O3 n +1 ( n =2) as a potential candidate for n -type thermoelectric (TE) oxides. The TE properties of 5 at.% La-, Nd-, and Nb-doped Sr3 Ti2 O7 polycrystalline ceramics were investigated and the origin of Seebeck coefficient was discussed from the viewpoint of the symmetry of TiO6 octahedra. A significant reduction in the lattice thermal conductivity was observed by the enhancement of phonon scattering at SrO/(SrTiO3 ) n interfaces originating from the inherent superlattice structure, and the maximum dimensionless figure of merit, ZT ∼0.15, at a 1000 K value was obtained in 5 at.% La-doped Sr3 Ti2 O7 . 相似文献
110.
Potassium titanoniobate (KTiNbO5) polycrystalline powders were synthesized by the sol-gel method and a novel preparation route which was described as a combination technique of the sol-gel process and solvothermal treatment. The synthesis processes, the structure and morphology characterizations for the as-prepared KTiNbO5 particles were investigated by using thermal analysis, X-ray powder diffraction, electron microscopy and other techniques. The KTiNbO5 particles synthesized in this work showed various morphologies depending on the different reaction processes. The KTiNbO5 compound obtained through 2-propanol solvothermal treatment exhibited unique particle morphology characteristic of sphere shape with the average size of 300 nm in diameter. In addition, the result that the formation of the spherical particle shape occurred during the solvothermal process was demonstrated. 相似文献